diff options
| -rw-r--r-- | kernel/exit.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/kernel/exit.c b/kernel/exit.c index 5d30019ff953..2116aace6c85 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -1302,9 +1302,15 @@ static int wait_task_continued(struct wait_opts *wo, struct task_struct *p) static int wait_consider_task(struct wait_opts *wo, int ptrace, struct task_struct *p) { + /* + * We can race with wait_task_zombie() from another thread. + * Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition + * can't confuse the checks below. + */ + int exit_state = ACCESS_ONCE(p->exit_state); int ret; - if (unlikely(p->exit_state == EXIT_DEAD)) + if (unlikely(exit_state == EXIT_DEAD)) return 0; ret = eligible_child(wo, p); @@ -1325,7 +1331,7 @@ static int wait_consider_task(struct wait_opts *wo, int ptrace, return 0; } - if (unlikely(p->exit_state == EXIT_TRACE)) { + if (unlikely(exit_state == EXIT_TRACE)) { /* * ptrace == 0 means we are the natural parent. In this case * we should clear notask_error, debugger will notify us. @@ -1352,7 +1358,7 @@ static int wait_consider_task(struct wait_opts *wo, int ptrace, } /* slay zombie? */ - if (p->exit_state == EXIT_ZOMBIE) { + if (exit_state == EXIT_ZOMBIE) { /* we don't reap group leaders with subthreads */ if (!delay_group_leader(p)) { /* |